The invention relates to a tomographic apparatus for the production of transverse layer images of a radiography subject, comprising a radiation measuring arrangement including a radiation source, which generates a radiation beam penetrating the radiography subject and having a cross-sectional extent perpendicular to the layer plane approximately equal to the layer thickness, and a radiation receiver with an array of measuring channels which converts the radiation intensity behind the subject into corresponding electrical signals, comprising a rotating device for the measuring arrangement, and comprising a measurand converter for the transformation of the signals delivered by the radiation receiver into a layer image, wherein, in every measuring channel of the radiation receiver, an individual detector and an amplifier circuit are disposed.
A tomograph of this type is described, for example, in the German OS No. 2,627,433. This tomograph, a so-called computer tomograph, permits the computation of the attenuation values of image points, arranged in a matrix in the examined layer, and the image display of these attenuation values. For every measuring channel it must be taken into consideration here that, in the case of a switched-off x-ray tube; i.e., during the signal interruptions, the measuring channel-output signal can deviate from zero due to zero point drifting occurring in the channel amplifier. This deviation is to be taken into account during the processing of the measuring signals at the channel outputs.